First create a new 1280×720 sequence and drag the video onto the timeline. Open the Effect Controls panel for the clip. Click the arrow next to the Motion effect to reveal the controls. The next step will depend on how you would like the final output to appear:
Option 1) Crop the top and bottom: Change the Vertical position to move the clip up or down and trim the edges as desired. Use keyframes to change the setting at the start and end of each shot you would like to crop differently.
Option 2) Downscale and add pillars: Set Scale to 90%. When encoding, enable Maximum Render Quality in the Export panel (optional). Note: You can achieve the same result just by exporting the video at 1280×720 without creating a new sequence.
Option 3) Squeeze vertically: Disable Uniform Scale, set Scale to 90%, and leave Scale Width at 100%. Enable Maximum Render Quality in the Export panel (optional).